Abstract               Background and objectives: Subclinical hypothyroidism is defined as a mild elevation in thyroid stimulating hormone (TSH) levels in patients along with normal serum T3 and T4 levels. The prevalence of this condition is higher in women than men. SCH patients are more likely to develop overt hypothyroidism and in future can go in for other complications .There are very few studies highlighting on the age group more susceptible for this disorder. This study was designed to detect the distribution of age more at risk of developing subclinical hypothyroidism. Materials and Methods: 200 patients with Subclinical hypothyroidism was included in the study group. Serums T3, T4, TSH were estimated by ELISA method. Thyroid abnormalities were diagnosed on the basis of these laboratory results, Results and Interpretation: From the total number of 100 patients with subclinical hypothyroidism enrolled in the study, 44 patients in the age group of 56 to 65 years of age had subclinical hypothyroidism. Significant increase was found in the mean serum levels of TSH (P<0.001).the number of cases presenting with sub clinical hypothyroidism increased with the increase in the age groups involved in the study. Conclusion: The present study has identified that the prevalence of subclinical hypothyroidism is more common in woman and pattern of distribution of subclinical hypothyroidism increases as the age advances. The number of patients presenting with subclinical hypothyroidism increases with increasing age and is more common between the age group of 56 to 65 years.

Key Words: Subclinical hypothyroidism, hypothyroidism, age distribution.

 

 

 

 

INTRODUCTION

SCH is also termed as mild hypothyroidism, is a condition in which there are small increase in the thyroid-stimulating hormone, in presence of normal circulating levels of T3 and T4 hormones. This condition is found twice in women as compared to men¹. Thyroid hormones are being found to have important effects on the synthesis, transport and metabolism of lipids². Inspite of diagnosing this condition at the early stages it has been observed that a small percentage of these patients advance to overt hypothyroidism, there is a lot of controversy whether elderly individuals have to be screened for subclinical hypothyroidism or the younger ones^3-5. It is still controversial aspect whether to screen patients for subclinical hypothyroidism. It is again found to be inevited that the early treatment will benefit this disorder from going in for frank hypothyroidism and other complications. A few studies have found that persons with subclinical hypothyroidism after treatment with L-thyroxine have shown some improvements (6-8). There are very few studies highlighting on the age specific distribution of SCH. The present study shows the importance of knowing the age group of people more susceptible for SCH so that they can be treated early and can be prevented from further complications.

 

MATERIALS AND METHOD

The study was done in the Dept. of Biochemistry, BLDEU’S Shri. B. M. Patil Medical College Hospital and Research Centre, Bijapur (Karnataka) India. 100 subclinical hypothyroid cases with the age of 15 years to 65 years were included in the study according to the inclusion and exclusion criteria considered for the study . This study was approved by the Institutional Ethics Committee. All the subjects gave an informed consent before undergoing further investigations. The study was carried out from November 2011 to May 2013.

Inclusion Criteria: Subclinical hypothyroidism cases having TSH in the range of 4.50 to 14.99 mlU/L, T3 and T4 within normal limits. Age group above 15 years and below 65 years were included in the study.

Exclusion Criteria: Cases with known hypothyroidism, thyroidectomy cases, patient with radiotherapy, previous radioactive iodine therapy, consumption of drugs known to cause SCH, primary or secondary dyslipidemia, patients with diabetes mellitus, patients with other systemic illness, renal and hepatic failure cases, patients on statins were excluded from the study.

Collection of blood samples: Venous blood samples were drawn at 8 a.m. following a 12 hours of fasting, in a plain bulb from the subjects, with all the aseptic precautions. Blood samples were centrifuged within 30 minutes at 3000 rpm for 5 min. and serum was separated. Serum samples were stored at -20°C until assayed. Serum T3, T4, TSH were estimated by ELISA method^9-11.

 

RESULTS

 

 

Figure 1: Shows the age distribution of subclinical hypothyroidism cases

 

Fig 1 shows the age distribution of subclinical hypothyroidism. From the figure it is evident that the subclinical hypothyroidism risk increases with increasing age and is maximum at the age group of 56 years to 65 years.

 

DISCUSSION

Our study showed that the occurance of subclinical hypothyroidism increases with age. According to our study we found that 4 cases presented in the age group of 15-25 years, 9 cases between 26-35 years,12 cases between 36-45 years, 31cases between 36-45 years, 44 cases between 36-45 years of age. Our study is similar to the study done by Sawin CT et al who studied The aging thyroid: thyroid deficiency and showed that occurance of subclinical hypothyroidism increases with age¹². Our study showed the same results as study done by Tunbridge WMG et al who studied The spectrum of thyroid disease in a community and found that this condition is more common in the elderly and is found twice as often in women as in men¹³. In a study done by Danese MD et al as who studied the Effect of thyroxine therapy on serum lipoproteins in patients with mild thyroid failure they found that SCH is uncommon in younger persons, but by the age of 65 years, the overall prevalence of the disorder is about 17% in women and 7% in men (14) our study is in accordance with their study.

 

CONCLUSION

From the present study it can be concluded that sub clinical hypothyroidism is less common at the younger age group and goes on increasing with the increase in age and is maximum at around the age group of 56 to 65 years. Knowing of the age specific distribution it becomes easier to screen those patients which can help in early diagnosis and treatment . It also points to the fact that the patients can be prevented from progressing to overt hypothyroidism and complications associated with it.

 

REFERENCES

1. Hueston WJ., Pearson WS. (2004): Subclinical Hypothyroidism and the Risk of Hypercholesterolemia. Ann Fam Med; 2(4): 351–355.
2. Cappola AR., Ladenson PW. (2003): Hypothyroidism and atherosclerosis. Journal of Clinical Endocrinology and Metabolism; 88: 2438–2444.
3. Franklyn J. Subclinical hypothyroidism. Clin Endocrinol (Oxf). 1995; 43:443-444.
4. Cooper DS. Subclinical thyroid disease: a clinician’s perspective. Ann Intern Med. 1998; 129:135-137.
5. American College of Physicians. Screening for thyroid disease. Ann Intern Med. 1998:129:141-143.
6. Cooper DS, Halpern R, Wood LC, Levin AA, Ridgway EC. L-thyroxine therapy in subclinical hypothyroidism: a double-blind, placebo-controlled trial. Ann Intern Med. 1984:101:18-24.
7. Nystrom E, Caidahl K, Fager G, Wikkelso C, Lundberg PA, Lindstedt G. A double-blind cross-over 12-month study of L-thyroxine treatment of women with ‘subclinical’ hypothyroidism. Clin Endocrinol (Oxf). 1988; 29:63-75.
8. Jaescheke R, Guyatt G, Gerstein H, et al. Does treatment with L-thyroxine infl uence health status in middle-aged and older adults with subclinical hypothyroidism? J Gen Intern Med. 1996; 11:744-749.
9. Wang S, Teng WP, Li JX, Wang WW, Shan ZY; Effects Of Maternal SubclinicalHypothyroidism On Obstetrical Outcomes During Early Pregnancy. J Endocrinol Invest., 2012; 35(3): 322-325.
10. Goel P, Kaur J, Saha PK, Tandon R, Devi L; Prevalence, associated risk factors and effects of hypothyroidism in pregnancy: a study from north India. Gynecol Obstet Invest., 2012; 74(2): 89-94.
11. Soos M, Siddle K. Characterization of monoclonal anti- bodies directed against human thyroid stimulating hor- mone. J Immunol Methods 1982; 51(1): 57-68.
12. Sawin CT, Castelli WP, Hershman JM, McNamara P, Bacharach P. The aging thyroid: thyroid defi ciency in the Framingham study. Arch Intern Med. 1985;145:1386-1388
13. Tunbridge WMG, Evered DC, Hall R, et al. The spectrum of thyroid disease in a community: the Whickham survey. Clin Endocrinol (Oxf).1977;7:481-483.
14. Franklyn J. Subclinical hypothyroidism. Clin Endocrinol (Oxf).1995; 43:443-444.